HOUSE MITES – A CAUSE OF PERENNIAL ALLERGIC RHINITIS

Although they are just one of many forms of insects with whom we share our living quarters, mites are the most important from an allergy perspective. A subclass of arachnids, two species of these microscopic creatures account for the majority of “house mite” allergies: Dermatophagoides pteronyssinus and Dermatophagoides farinae. One or both may be present in a home at any time. Cleanliness of the home or its occupants has nothing to do with their presence.
Mites need three things to survive: food, proper conditions of humidity, and safety. All three are found in homes. Their primary food source is shed skin cells from the human inhabitants and pets or feather-stuffed bedding and furniture. Skin shedding occurs in areas where humans spend the most time when at home, so there is good reason why the highest concentration of mites is found in stuffed furniture, carpeting, mattresses, and bedding. They also accumulate in clothing and stuffed toys.
The old saying “safe as a bug in a rug” should be the house mite motto. These microscopic creatures burrow deep into upholstered furniture, stuffed toys, bedding, and loose, long-pile carpet. Here, moisture conditions are optimal for survival and the mites are sufficiently protected so as to be impervious to vacuuming and other human efforts to eradicate them. Or, at least they were.
Modern living – central heating, better sealed homes, and wall-to-wall carpeting – has benefited both man and mite. Mites require very specific conditions of humidity in relation to temperature for survival. Ideal conditions encompass a relative humidity of 55 to 75 percent over a temperature range of 59 to 95 degrees F. What better place than a home at 70 degrees F and a relative humidity of greater than 60 percent? Still, because temperature and humidity conditions vary greatly throughout the United States, the concentration of mites is greater in some areas than in others.
Mites have no lungs. They take air and water into their bodies primarily by diffusion through their shells. Thus, the greater the relative humidity, the greater their ability to acquire water. Their humidity needs are generally satisfied indoors, particularly in the winter months when the central heating system is functioning. In general, a combination of relative humidity of 40 to 50 percent and a temperature of 82 to 83 degrees F (28 to 34 degrees C) prohibits mite survival. So, whereas mites are found in most homes in the states bordering the east and gulf coasts, they occur in only a minority of homes in the states along the Rocky Mountains.
People are allergic to the mite fecal pellet. A single mite will produce some 200 times its weight in these potent, highly allergenic fecal pellets during its short lifetime (about 4 weeks). Once expelled, the pellets break down, incorporate into the dust of the house and become airborne when the carpet, bedding, furniture, and so on are disturbed. Microscopic in size, these particles are easily inhaled into the nose and lungs, where they trigger allergy symptoms. The density of the live mite population in your home determines the degree of problem you will have with mite fecal particles. Although dead mites and their body parts do become airborne, they do not contribute significantly to mite allergy.
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HOUSE MITES – A CAUSE OF PERENNIAL ALLERGIC RHINITISAlthough they are just one of many forms of insects with whom we share our living quarters, mites are the most important from an allergy perspective. A subclass of arachnids, two species of these microscopic creatures account for the majority of “house mite” allergies: Dermatophagoides pteronyssinus and Dermatophagoides farinae. One or both may be present in a home at any time. Cleanliness of the home or its occupants has nothing to do with their presence.Mites need three things to survive: food, proper conditions of humidity, and safety. All three are found in homes. Their primary food source is shed skin cells from the human inhabitants and pets or feather-stuffed bedding and furniture. Skin shedding occurs in areas where humans spend the most time when at home, so there is good reason why the highest concentration of mites is found in stuffed furniture, carpeting, mattresses, and bedding. They also accumulate in clothing and stuffed toys.The old saying “safe as a bug in a rug” should be the house mite motto. These microscopic creatures burrow deep into upholstered furniture, stuffed toys, bedding, and loose, long-pile carpet. Here, moisture conditions are optimal for survival and the mites are sufficiently protected so as to be impervious to vacuuming and other human efforts to eradicate them. Or, at least they were.Modern living – central heating, better sealed homes, and wall-to-wall carpeting – has benefited both man and mite. Mites require very specific conditions of humidity in relation to temperature for survival. Ideal conditions encompass a relative humidity of 55 to 75 percent over a temperature range of 59 to 95 degrees F. What better place than a home at 70 degrees F and a relative humidity of greater than 60 percent? Still, because temperature and humidity conditions vary greatly throughout the United States, the concentration of mites is greater in some areas than in others.Mites have no lungs. They take air and water into their bodies primarily by diffusion through their shells. Thus, the greater the relative humidity, the greater their ability to acquire water. Their humidity needs are generally satisfied indoors, particularly in the winter months when the central heating system is functioning. In general, a combination of relative humidity of 40 to 50 percent and a temperature of 82 to 83 degrees F (28 to 34 degrees C) prohibits mite survival. So, whereas mites are found in most homes in the states bordering the east and gulf coasts, they occur in only a minority of homes in the states along the Rocky Mountains.People are allergic to the mite fecal pellet. A single mite will produce some 200 times its weight in these potent, highly allergenic fecal pellets during its short lifetime (about 4 weeks). Once expelled, the pellets break down, incorporate into the dust of the house and become airborne when the carpet, bedding, furniture, and so on are disturbed. Microscopic in size, these particles are easily inhaled into the nose and lungs, where they trigger allergy symptoms. The density of the live mite population in your home determines the degree of problem you will have with mite fecal particles. Although dead mites and their body parts do become airborne, they do not contribute significantly to mite allergy.*17/322/5*